Pipelines are used to transport fluids in various industries, including chemical, oil and gas, and manufacturing. These industries use processes that require fluid flow rates to be accurately measured. These measurements are performed at locations known as meter stations. Typical meter stations comprise a meter tube provided with a flow conditioner and a flow meter, e.g., an ultrasonic flow meter, operatively coupled with the meter tube to measure fluid flow.
Flow meters function in different ways. They can use: differential pressure of the fluid across an obstruction, ultrasonic signal travel times, turbine blade rotational speed, Coriolis forces, or even electrical and magnetic fields being generated due to bulk fluid movement. Almost all of these measurement methods require use of the fluid velocity distribution, known as a velocity profile, a velocity flow profile or a flow profile.
Ultrasonic meters are frequently designed to operate optimally within particular Reynolds Number ranges. Reynolds Numbers for several products for which an ultrasonic meter may be used to measure are shown in FIG. 1. Use of an ultrasonic flow meter to measure fluid flow for a product in a Reynolds Number range for which the ultrasonic meter is not rated can lead to inaccurate measurements.
While industry has recognized the measurement challenges presented in measuring flow profiles over the range of Reynolds Numbers, industry has focused its efforts on improving ultrasonic meter design using complex calibration algorithms and virtually ignored the role of the meter tube in measurement process.
Accordingly, there is a need for metering tubes that improve the accuracy of ultrasonic flow meters.